The present invention relates to a semiconductor device and a data transmission method and, for example, to a semiconductor device including an insulation coupler and a data transmission method.
When transmitting and receiving signals between a plurality of semiconductor chips with different power supply voltages, it is necessary to provide electrical insulation between the semiconductor chips using an insulation coupler and transmit and receive signals. As the insulation coupler, an AC coupler using a capacitor, coil or the like, a photo coupler and the like are known. A semiconductor device that transmits and receives signals using a coil as the insulation coupler is disclosed in U.S. Pat. No. 6,262,600, U.S. Pat. No. 7,075,329, U.S. Pat. No. 7,302,247, and Kaeriyama et al. (“A 2.5 kV isolation 35 kV/us CMR 250 Mbps 0.13 mA/Mbps digital isolator in standard CMOS with an on-chip small transformer”, 2010 Symposium on VLSI Circuits, Technical Digest of Technical Papers, 2010, pp 197-198).
In the case of transmitting a data signal from a transmitting circuit on one semiconductor chip to a receiving circuit on another semiconductor chip using an insulation coupler, according to the technique disclosed in U.S. Pat. No. 6,262,600, a pulse signal is transmitted during the period when the data signal is H (High) level and not transmitted during the period when the data signal is L (Low) level.
On the other hand, according to the technique disclosed in Kaeriyama et al. and U.S. Pat. No. 7,075,329, a pulse signal is transmitted once or twice from the transmitting circuit, triggered by the edge of the data signal. The pulse signal that allows distinction between the rising edge and the falling edge of the data signal is transmitted from the transmitting circuit. Thus, the data signal can be restored in the receiving circuit.
Because the technique disclosed in Kaeriyama et al. and U.S. Pat. No. 7,075,329 transmits the pulse signal only at the edge of the data signal, it has an advantage over the technique disclosed in U.S. Pat. No. 6,262,600 that keeps outputting the pulse signal during the period when the data signal is H level in that power consumption and radiation noise are lower. Note that the both techniques are disclosed in U.S. Pat. No. 7,302,247.